Telephone-switchboard.



Patented May 2|, 1901'.

H. ARDOUGLAS TELEPHONE SWITCHBDARD.

(Application filed Nov. 2, 1898.) (No Model.) 3 Sheets-Sheet I.

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Patented May 2|, 190i. H. A. DOUGLAS. TELEPHONE SWITCH BOARD.

(Application filed Novi'fl, 1898.)

3 Sheets-Sheet 2.

000080808000 m mm 5 00080080088 m x mm @QQQQQQQQQQQQQ m mmm m OODOOOQQQOOOQQO m mm 000088080009 m mm mm 00 I. I D 00 l 00 i 0 I no IIIIIID oo it on ll IIII Do on a 0 o v 0 no l (No modem UNITED STATES PATENT OFFICE.

HAROLD A. DOUGLAS, OF GRAND RAPIDS, MICHIGAN, ASSIGNOR TO PETER O. BURNS, OF CHICAGO, ILLINOIS.

TELEPHONE-SWITCHBOARD.

SPECIFICATION forming part of Letters Patent No. 674,402, dated May 21, 1901.

I Application filed November 2, 1898. Serial No. 695,273. (No model.)

To all whom it nutty concern.-

Be it known that I, HAROLD A. DOUGLAS,

a citizen of the United States, residing at Grand Rapids, in the county of Kent and State of Michigamhave invented a certain new and useful Improvement in Telephone- Switchboards, of which the following is a specification.

My invention relates to certain improve- IO ments in telephone-switchboards' known as transfer or trunking-board systems.

At the central exchange of a telephone system a switchboard is employed for the purpose of temporarily connecting together a multiplicity of subscribers lines, whereby conversation may be carried on between any two subscribers of the system. A comparatively small number of subscribers may be connected and disconnected with facility on a small board; but as the number of subscribers increases, necessitating the employment of operators located at remote points from each other in front of the switchboard, the problem of connecting and disconnecting becomes'complicated and difficult. Two systems are now more generally used, known, respectively, as the trunking-board system and the multiple-board system. .In the latter the switchboard is divided into sec- 0 tions and the lines of all the subscribers are provided with means for interconnection on each of the sections, whereby an operator at any one of the sections may make connec-v tion between any two lines of the entire system. In the former or trunking-board system the lines of the subscribers are (1ivided into groups, each of which groups are terminated upon the respective sections. In such a system an operator at a given section 40 may establish a connection between two lines grouped upon that section; but to make connection with a line of the group of that section and a line ofa group terminating at another section it becomes necessary to provide means for signaling and communication between the two sections in: order that the two operators may cooperate with one another to establish'the desired connection-in some cases what are called the trunkingsectionandtrunking operator. 'lhelines which may be connected by any one operalprovements.

tor on her section without the intervention of any other operator are termed local lines, while lines which terminate in other sections requiring the cooperation of two operators in relation. to the local lines are termed foreign lines.

The'object of my invention is to provide a positive means of signaling between the operators, whereby the operator at the foreign 6o or distant section or groups may be signaled by the local operator, and in accomplishing this result to provide means whereby the act of making or breaking the connection at the local sections gives a signal at the trunking or foreign section, which signal is withdrawn as the operator at the trunking or foreign section proceeds to make a connection and which signal is again given should the trunking or transfer operator proceed to discon- 7o nect when the line is still in use.- I

My invention has certain other objects in view; and it consists in certain features about to be described, reference being now had to the accompanying drawings, in which- Figure 1 is adiagrammatic view of the circuit arrangement. Fig. 2 is a face view of a portion of switchboard embodying my im- Fig. 3 is a side view of the trunking or foreign section. Fig. 3 is a hori- 8o zontal section of a portion of the same. Fig. 4 is a detail view of the transfer-jack. Fig. I 5 is a detail perspective view showing the manner of effecting contact. Fig. 6 is a View of the transfer-jack and the transfer-plug inserted therein. Fig. 7 is an elevation of a portion of the foreign section of the board, showing the seat or socket for the foreign transfer-plug. Figs. 8 and 9 are vertical sections of the same, the former without the plug and the latter with the plug inserted. Fig. 10 is a horizontal section taken on line 10 10 in Fig. 7.

The subscribers stations are designated at A and A the station A being the callingand 5 station A the called subscriber. The lines 1 and 2 of the calling-station are led to the spring-jack B on the switchboard after passing through the calling-annnnciator B These instru mentalities are of the ordinary construc- I00 tion. The plug B of the subscribers jack B is connected through the operators listening is: w.

and ringing key 13 this construction and arrangement being of the usual character. The clearingout drop B is included, as is usual, in the cord-circuit of the plug B Assuming that it is desired to establish a connection between the circuits of two differ ent groups of subscribers lines-as, for instance, between the circuits of stations A and A terminating on different sectionsthe operator inserts the plug D in the transferjack E. It comprises a battery spring-strip e, which is normallyin contact with the transfer or signaling circuit controlling springstrip f. The other battery spring-strip, h, is normally out of contact. The line-springj is connected to the limb 3 of the trunking circuit, the otherlim b, l,of which is connected to the frame of the jack. At the trunkingsection a signaling instrumentality is provided, in this instance the incandescent lamp H, included in the line 5, connected with the controlling-spring f of the jack E. This line 5 is also connected to the circuitcontrolling spring J of the transfer-plug seat K in series with the lamp H.

The transfer-plug seat K comprises a plugsocket 7t and the controlling-spring Jand the battery-spring m. The controlling-spring J is norinallyin contact with the battery-spring m when the plug is inthe socket 7c. The battery L is connected by the common batteryleads 6 and 7, with the battery-springs e and h of the jack E, and also with the batteryspring m and the frame of the plug-seat K by the limbs 8 and 9, connected to the leads 6 and 7.

The transfer-plug is designated M.

The transfer order-circuit is connected in the ordinary and usual manner, my invention residing in the means of eifecting transfer-signals.

The operation of my device is as follows: When the plug D, corresponding to the other plug, B of the pair andinserted in the switchboard-jack, is inserted in the transferjack E, the normal contact of the controlling-spring f with the battery-spring e is broken and a contact made between battery-spring h and the controlling-springf, and as the transferplug M at the transfer-section is now in its socket 7c the circuitis closed through battery L as follows: from battery-spring h of jack E, through common batterylead 6, battery L, branch 8, to controlling-spring j of plugsocket 70, through the lamp h and return-lead 5 to spring f of jack E. Thus the lamp His excited by battery L to display a signal. This lamp-signal informs the operator from what section the call is extended, as it displays the number of the trunk-line over which the connection is to be made. The transfer operator is then notified in the usual manner over the common order-circuit of the number of that subscribers line with which connection is desired. She thereupon removes the transferplug M of the trunk-circuit over which the signal is extended-4n this instance, as shown,

the circuit-leads 3 and 4and then inserts the said plug in the subscribers jack of the called-subscribers linein this instance the jack M of the subscriber A The removal of the plug M breaks the contact between controlling-spring J of plugeseat K and the battery-spring m, thus opening the common battery-circuit and cutting out the battery L, thereby extinguishing the lamp I1 and withdrawing the signal. As the cords of the plug M are connected with the leads 3 and 4 and springs J and frame of jack E, as shown, the conversation may be carried on over the established circuit between the subscribers stations A and A When the subscribers answering operator is notified by means of clearingout drop in the usual way that conversation is completed, she withdraws the plug D from the transfer-jack E, restoring the normal connection between con-trollingspring f and the battery-spring (2, thereby closing the common battery-circuit through common battery-lead 7, battery L, branch 9, controlling-spring J of plug-seat K, lamp H, and return-wire 5. The lamp is then excited to display a signal, and as the connection is established this is a notification to the trans fer operator to disconnect, which is accomplished by removing the plug M and replacing it in the plug-socket 7c of the pl ug-seat K.

Should the transfer operator by mistake remove the plug M while the connection is still in use by the subscribers, the lamp H will .be excited to display a signal notifying the operator of hererror. This results be cause the controlling-spring J of plug-seat K contacts with battery-spring m, as the plug M when withdrawn automatically reseats in plug-socket 713, the connections being the same as hereinbefore described.

It will be observed that when the lamp II is lighted to attract the attention of the operator at the transfer-board to make a connection the plug D of the main board is in position within the trunking-jack E thereof and the transfer-plug M is in position within the plug-seat K of the transfer-board, and also that when the lamp is lighted for the purpose of having the transfer operator disconnect established connections both of these plugs are out of their respective jacks. further observed that in the normal condition of the apparatus, either before a connection with the transfer-board has been made or after one has been broken, the main-board trunking-plug D is out of its jack E, while the transfer trunking-plug M is in position within its seat K, and also that during the establishment of a connection the plug D is in position within its jack E, while the plug M is out of its seat K. In other words, the lamp H is lighted when the trunkingplug D is in position in its jack, and the plug M in position in its seat and also when said plugs are out of said jack and off said seat, respectively; but said lamp is not lighted when either the plug D is in its jack and the plug It will be board, of a transfer spring-jack on said main M off from its seat or the plug D out of its jack and the plug M on its seat. It will thus be seen that the connection of the battery L with the jack E and the seat K is such as .toinclude the lamp H in the battery-circuit when the plug D is in its jack and the plug M on its seat and also when the plug D is out of its jack and the plug M off from its seat and to out said lamp out of such circuit when either the plug D is in its jack and the plug M off from its seat, or vice versa.

Having thus described my invention, what I claim as new therein, and desire to secure by Letters Patent, is-

1. In a telephone system, the combination with a main switchboard and a transferboard and a plug-seat on said transfer-board, a tru nk-circuit extending between said boards and terminating at the main board in said spring-jack, a connecting-plug for the other or transfer end of said trunk-circuit normally seated within said seat, an operators connective means at the main board including a connecting-plug,asignaling device associated with said seat, a generator to operate said device; and circuit connections from said generator and device to the said jack and seat for operating the device when an operators plug is in the jack and the trunk-plug is in its seat and a so when the trunk-plug is out of its seat and the operators plug is withdrawn from the jack.

2., In a telephone system, the combination with a main switchboard and a transfer-board, of a transfer spring-jack on said main board and a plug-seat on said transfer-board, a trunk-circuit extending between said boards and terminating at the main board in said spring-jack, a connecting-plug for the other or transfer end of said trunk-circuit normally seated within said seat, an operators connective means at the mainboard including a con meeting-plug, asignaling device associated with said seat, a generator to operate said device; and circuit connections from said generator and device to the said jack and seat for rendering the said device operative when an operators plug is in the jack and the plug is in its seat and also when the trunk-plug is out of its seat and the operators plug is withdrawn from the jack, and for rendering the same inoperative at all other times.

3. In a telephone system, the combination with a main switchboard and a tran sfer-board, of a transfer spring-jack on said main board and a plug-seat on said transfer-board, a trunk-circuit extending between said boards and terminating at the main board in said spring-jack, a connecting-plug for the other or transfer end of said trunk-circuit normally seated within said seat, an operators connective means at the main board including a con meeting-plug, asignaling device associated with said seat, a generator to operate said device; circuit connections for said generator and device to said jack and seat comprising a conductor from each pole of the generator to the said jack and seat, another conductor from the jack to the seat including the said signaling device; and contacts in the said jack and seat normally connecting said signaling-conductor with the same pole of the generator, and for disconnecting it therefrom and connecting the other pole thereto when an operators plug is in the jack or the trunkplug is removed from its seat.

4. In a telephone system, the combination with a main switchboard and a transfer-board, of a transfer spring-jack on said main board and a plug-seat on said transfer-board, a trunk-circuit extending between said boards and terminating at the main board in said spring-jack, a connecting-plug for the other or transfer end of said trunk-circuit normally seated Within said seat, an operators connective means at the main board including a connecting-plug, a signaling device associated with said seat, a generator to operate said device; contacts in the jack and seat con nected with each side of the generator, another contact in the jack and also in the seat and operatively connected with the signaling device and normally in contact with the same side of the generator, said latter contacts being disconnected therefrom and thrown into contact'with the other side of the generator when an operators plug is in the jack or the trunk-plug is removed from its seat.

5. In a telephone system, the combination with a main board and a transfer-board, trunk-circuits therebetween, a signaling device for each trunk at the transfer-board, a generator, signaling-circuits extending between the two boards comprising a common conductor including the said device, and conductors from each side of the generator, the said common conductor being normally connected at the two boards with a conductor from the same pole of the generator and means to throw said common conductor into contact with the conductor from the other pole in initiating and completing connections through the trunk.

In testimony whereof I affix my signature in presence of two witnesses.

HAROLD A. DOUGLAS.

Witnesses: v

CHAS. C. BULKLEY, L. M. BULKLEY.

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